I'm jumping the gun here and buying my cousins 2003 RS6 with 108k miles, My first....

[JoeJITSU]

My first upgrade will be a Tune. Can you tell me what tune is the best bang for the buck?

Since it already has 450HP, I will likely just do a chip, exhaust, DP and likely a FMIC.

I'm moving from a 312whp Legacy GT wagon to this. So I am pretty stoked.


:)

[moyenecorniche]

Congratulations on joining the Family...
However, your first order of business with this RS6 is to go over its mechanical health in a close inspection. With 108k miles it more than likely needs a few replacements. So first check all coolant connections and all gaskets. Because of the immense heat in the engine bay of all performance Audi's, the connections to plumbing crystalize and begin to fail.... Next would be a check of the internals, as in leak down and compression tests. New plugs and coil packs are always a good idea.
Lubricants, motoroil and filter change, need to check if any residue is at the bottom of your oil pan, that will tell you if you need to look further inside the motor. @ 108,000 differential fluid replacement is also a good idea...

Now for the ciritcally important parts... V8 twin turbo's. (a) those twin screws need attention as to their condition... Both because if one is in need of replacement then both have to be replaced as they need to be matched... Here is one of your wallet draining potentials. (b) You have 2 intercoolers on each front side. Deleting those and installing an FMIC is not a good idea. You are not going to improve on Audi's engineering here. The RS6 was well thought out. There's more then plenty of cold air for the V8's requirements at a much higher HP setting...

Next would be suspension items. Might be a good idea to look into replacing all the rubber bushings with a harder urethane compound. Springs and dampers next. All control arms should be reviewed. Since we're down below... Brakes, you have Brembo's, may very well be time to up the performance by better pads and lighter rotors...
That's about it for the preliminary list.....

Make sure its healthy and up to spec, live with the car for a while and do some research in the RS6 Forum section....

Have fun but don't trash it by wanting to add A4 2.0T mods... There's only 1,200 of these in the USA ( 1,290 if you add Canada )

[Audibot]

Also, for future reference, you will want to post in the C5 A6/S6/RS6/allroad section.

On top of what was said above, typically at 100k or so, bushings and rubber components begin to go. So you may be looking at replacing control arms and mounts.

[JoeJITSU]

Congratulations on joining the Family...
However, your first order of business with this RS6 is to go over its mechanical health in a close inspection. With 108k miles it more than likely needs a few replacements. So first check all coolant connections and all gaskets. Because of the immense heat in the engine bay of all performance Audi's, the connections to plumbing crystalize and begin to fail.... Next would be a check of the internals, as in leak down and compression tests. New plugs and coil packs are always a good idea.
Lubricants, motoroil and filter change, need to check if any residue is at the bottom of your oil pan, that will tell you if you need to look further inside the motor. @ 108,000 differential fluid replacement is also a good idea...

Thank you.
Now I was researching and I am not sure if this is true but does the Timing belt really have to be changed every 35k miles?

[Kevin1]

Thank you.
Now I was researching and I am not sure if this is true but does the Timing belt really have to be changed every 35k miles?

It's true. You are looking at a high maintenance vehicle

[moyenecorniche]

That I don't know, the guys in the RS6 section will answer that one for you... I know this. After owning 3 Audi's, (1) 04 1.8T Atlas Gray Avant (2) 04 B6 S4 ( V8 I can relate ) (3) and an 05 C5 allroad V6TT I can say that the info and the tech help I have received from A-ziners here is second to none..

Its a great Forum with diehards who know what they are talking about, if you have a question then they're are people here who will have the correct answer....
In the end it means you get to enjoy your Audi and save a lot of grief and money in the long run...

[zcd2.7t]

My first upgrade will be a Tune. Can you tell me what tune is the best bang for the buck?

Since it already has 450HP, I will likely just do a chip, exhaust, DP and likely a FMIC.

I'm moving from a 312whp Legacy GT wagon to this. So I am pretty stoked.


:)

Please allow me to suggest that you first post your questions on rs6.com - there's a group of die-hard RS6 owners there who can give you some great advice regarding all things RS6.

Also, think carefully before pulling the trigger, because if you can't/don't want to work on the car yourself, an RS6 of that vintage can drain even a large bank account in no time.

Finally, the transmission is fragile, so think very carefully before tuning the car...

[2wookies]

Or give it all the boost and say screw it?

[dab]

good luck as I sold mine with 85k miles after having spent 10k on a new transmission with warranty and yes the timing belt has to be done and was included. As my signature says it was apr tuned as well as tiptronic, it is rumored that it is no longer available. I owned the car for 9 years and up until the last 5k miles I didn't have to do much with it.

[PKmode]

I was just about to point out the most common large maintenance expense with the C5RS6 is the ZF transmission failure. Should that be the case, I'd highly recommend swapping in a 01E manual trans from a B5S4/A6/AllRoad. Even then, you would want to have it rebuilt with a new 1-2 collar and the updated parts (snycro materials were changed) before putting it in as that transmission is known for the 1-2 collar failure but otherwise proven capable of large power and torque figures. This is not a cheap proposition. If you can do the labor yourself, expect in the area of $4K. If you need to pay for labor, easily add $2k+ at a reasonable indy. You'd want a guy who's done it before. I've done the job on a C5S6 and it's not that bad but I'm pretty experienced with a wrench.

[hubris]

good luck as I sold mine with 85k miles after having spent 10k on a new transmission with warranty

Why did you spend 10k with a warranty?!

[Brooklyn]

I read that to mean his new transmission came with a warranty, but it does read a bit confusing.

[Audibot]

Level 10 in North Jersey may be able to build you up a bulletproof transmission. I know they sell complete units for $5k-$6k, and if you send one to them, it's less. Could be worth it to give them a ring.

[dab]

I read that to mean his new transmission came with a warranty, but it does read a bit confusing.

that is correct, the new tranny had a 3 year warranty for the next buyer.